William e



(No Model.)

, W. E. ATHE'ARN. V POLE GHANGING KEY. No. 252,346 Patented Jan.17,1882."

gnaw Wot fUNITED. STATES PATENT OFFIC WILLIAM E ATHEARN, on NEW YORK, N.Y.

POLE-CHANGING KEY.

SPECIFICATION forming part of Letters PatentNo; 252,346, dated January1'7, 1882.

e Application filed October 26, 1881. (No model.)

To all whom it may concern:

Be it known that I, WILLIAM E ATHEARN, a citizen of the United States,residing at New York, in the county and State of New York, have inventedcertain new and useful I m provements in Pole-Changing Keys, of whichthe following is a specification.

A Myinvention relates to that class of telegraphic keys employed intransmitting messages by means of alternating positive and negativeelectriccurrents, commonly called pole-chan ging keys.

In making use of currents of alternating polarity for telegraphictransmission it has been customary to adopt one of two methods. Thefirst consists in permanently connecting the battery at thesending-station with the earth by a wire proceedingirom a point not farfrom midway between its poles, thus dividing the battery. into twoequal, or nearly equal, sections. Currents of alternating polarity aresent upon the line-wire by completing its circuit I first with onesection and then with the other of the divided battery. The secondmethod consists in connecting the opposite poles of a batteryalternately with the earth and with the line-wire. Thelatter-method isusually considered preferable in practicefhs it requires a battery ofonly one-half the number of elements, for the reason that the sameseries of battery-cells furnishes both the positive and negativecurrents.

My invention consists in certain improvements in the mechanicalconstruction of the pole-changing keys employed for transmittingcurrents after the method last describeddhat is, from the opposite polesof an undivided battery. I

In the accompanying drawings, Figure l is a plan View of myimproved keyor transmitter,

and Fig. 2 represents a side elevation of the same. Fig.3 is atheoreticaldiagram, showing the arrangement of circuits as applied tothe key.

Referring. to Figsl and i, A represents a supporting-base, of hardrubber or other suitable insulating material, upon which are mounted thekey and its attachments.

Thekey-lever B is mounted in the usual manner upon a metallic baseor'support, D, by means of its transverse axis I), which is mountedbeported by and are in electrical connection with the upper ends of thebolts d and e, respectively. These bolts extend downward through but areinsulated from the metallic base D and the supporting-base A, and serveto secure the key to the operators table and as bindingscrews for makingthe necessary circuit-connections. h

Against one side of the lever B is secured a block B of suitableinsulatin material such 7 7 b 7 as hard rubber, upon which is mounted aflexible arm or spring, F, bearing at its free end two contact-points, fand 9, preferably of platinum or other infusible metal. the arm F playsbetween two contacts, f and g, which are carried by the adjustablescrews L and M, supported upon the posts It and i. The spring F makescontact with one or the other, according as the lever B is raised ordepresse'd. At the opposite end of the arm F an adjustable screw,H,'proj ects through the block E and engages with the end'of a flexiblespring, h. The opposite end of this spring is electrically connectedwith an insulated bolt, It, thus placing the said bolt in electricalconnection with the arm F. v 7

It will be observed that byinsulating the adjustable screw H from thekey-lever and the binding-post h fromthe base I am enabled to employ thespring 71/ in the place of the coils of thin wire which have heretoforebeen used for making the necessary electrical connection betweenthestationary binding-post and the movable pole-changing arm. The springh tends to raise the end a of the key-lever, thus separating thecontact-points cl d and ff and closing the contacts 0 e and g g, whichis the normal position ot'the key lever. Thecontactpoints d and e areelectrically connected with the contacts g and 1'', respectively.

The arrangement of circuits will be more This end of readily understoodby reference to Fig. 3. In this figure K represents the main battery,one pole of which is connected by a wire, 3, with the contact-point c.This contact-point is also connected, as hereinbet'orestated,with thecontact-pointf by a wire, 2. The other pole of the battery K isconnected by a wire, 4, with the point (1, and also by the wire 5 withthe contact-point g. The flexible arm F is connected by awire, 1, withthe earth, while the key-lever B is connected with the line-wire 6, inwhich may be included the receiving-instrument N and a switch, 0, forcutting out the key when receiving.

Theoperation of the keyis as follows: When the key-lever is in itsnormal position a circuit is completed from the earth, through the wire1, arm F, contactsg and 9, wires 5 and 4, battery K, wire 3, contacts 6and e, and key-lever B, to the line-wire 6, sending a. positive currentfrom the battery K to line. By depressing the key-lever by means ofthebutton a the contacts 9 g and e e are separated and the contactsff and dd brought together. When the lever is in this latter position thecircuit is from the earth through the wirel, arm F, contactsf and f,wires 2 and 3, battery K, wire 4, key-lever B, and line-wire 6, sendinga negative current to the line. In this manner alternating positive andnegative currents are sent upon the line-wire by operating the key afterthe manner of an ordinary Morse key..

It will be seen by reference to Fig. 1 that it is essential to theproper working of the key that the contact-points be so adjusted thatthe circuit through the points'fand f or gaudy should be complete at themoment the circuit is closed through thecontactsd d or e 6,- other wisea wavering or irregular current would be transmitted. The screwsLandMshould there- I forebe so adjusted that the points upon the arm F shallstrike against their respective contacts f or g before a contact is madebetween the points 01 d or e e. The resiliency ofthe spring F will allowthe key lever to be moved until such contact is made, and by itspressure insure a reliable electrical connection.

I have shown and described my transmitter as being operated by hand, inthe same manner as an ordinary Morse key; but it is evident that anelectro-magnet and its armature may be applied in place of the button afor actuating it by means of a local battery and independent key, in awell-known manner. It is evident, moreover, that, instead of securingthe insulating-block B against the side, it may be placed at the endofthelever B. This change would make itnecessary to transfer the adjustable screw H to the opposite side of the axis 1) from that representedin the drawings. A suitable spring t'or exerting a downward pressureupon this screw would then be substituted for the springh for example, acoil-sprin g, which might be extended by depressing the button a.

I am aware that pole-changing keys have been constructed in which thekey-lever has been provided with contact-points vibratingbetweentwoyieldingsprings. Keys constructed upon this plan, however, areboth complicated and liable to become out of order by use.

It has, as before stated, been found necessary in the keys hitherto usedto employ thin wires for the purpose of making the necessary connectionswith the movable parts of the key, so as not to retard its movement.These are very liable to become broken and disarranged. The peculiarconstruction of the key herein desci ibed renders it free from theseobjections and at the same time convenient for manipulation.

I claim as my invention- 1. In a pole-changingkey or transmitter, thecombination, substantially as hereiubet'ore set forth, of apivotedlever,vibrating between and alternately making contact with twoindependent stationary contact-points, and a flexible arm secured to butinsulated from said lever, vibrating between two stationary adjustablecontact-points.

2. The combination, substantiallyas hereinbefore set forth, of thekey-lever and its metallic base, the insulated flexible arm, and thespring h, insulated from the lever and base,

but in electrical connection with the flexible arm. I

In testimony whereof I have hereunto sub scribed my name this 21st dayof October, A. D. 188]. Y

\VILL [AM E. ATHEARN.

Witnesses:

CHARLES A. TERRY, WILLIAM H. KENYON.

